Each working program has its priority. Windows kernel priority is highest, other programs work with normal priority. Why? We may increase any program's priority not loading processor! When you change window, PC Acelerate automatically increase foreground window priority (programs shortcut you see in system tray). Except this if free PC memory will decrease (after unloading a program from memory can remain already not working libraries), PC Accelerate preventive will unload them from memory in that moment, when you work more intensive and will support the free-memory volume on constant average level.